London: Alastair Cook was nearing his sixth century in nine Tests as England made a fine start to their final day push for a series-clinching win against Sri Lanka here at Lord's on Tuesday. (Agencies)
England were 260 for three in their second innings, a lead of 267, at lunch Tuesday's fifth day with 72 overs still left in the match.
Left-handed opener Cook, who made 96 in the first innings, was 87 not out and Ian Bell 13 not out.
It looked as if England would get through Tuesday's morning session without losing a wicket.
But, shortly before lunch, Kevin Pietersen was bowled by left-arm spinner Rangana Herath for 72 to end a third-wicket partnership of 127 with Cook.
It was the second time in as many matches Pietersen, arguably England's most talented batsman, had fallen to Herath and the 20th time in his Test career overall he'd been dismissed by a left-arm spinner.
Victory at Lord's would give England an unbeatable 2-0 lead in the three-match series after their innings and 14-run first Test win in Cardiff.
They resumed Tuesday on 149 for two, a lead of 156, with Cook 61 not out and Pietersen 15 not out.
Sri Lanka, as they had on Monday, took the field without injured captain Tillakaratne Dilshan.
A team spokesman said Tuesday the opening batsman had suffered a broken thumb caused by twice being hit by fast bowler Chris Tremlett during his innings of 193 - the highest individual Test score by a Sri Lankan at Lord's.
Cook, who had helped England recover from the loss of captain and opening partner Andrew Strauss for a duck, inflicted pain of a different sort on the tourists by square-cutting left-arm seamer Chanaka Welegedara for four.
An increasingly confident Pietersen then cover-drove and straight drove Welegedara for two authoritative fours in three balls.
But he did look uncertain against Herath, the pick of Sri Lanka's bowlers with two for 38 from 18 overs.
A quick single saw Pietersen to an 85-ball fifty including six fours.
Sri Lanka's attack, lacking a genuine fast bowler, struggled to make much of an impression on a typically good Lord's pitch.
But Pietersen, on 54, gave a difficult chance when wicketkeeper Prasanna Jayawardene, diving to his left, failed to hold a one-handed catch off a leg-glance against Dilhara
London: Alastair Cook was nearing his sixth century in nine Tests as England made a fine start to their final day push for a series-clinching win against Sri Lanka here at Lord's on Tuesday.